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通过对某水电工程坝区岩体结构的表生改造形迹调查，发现坝区除了发育与岸坡平行的正常的卸荷破坏方式外，还发育了一种破坏方式——夹泥型张裂隙。裂面性质的弱化和发育的普遍性，使这类破裂带可能成为控制坝区高边坡岩体稳定性的重要岩体力学边界。在其发育过程中的诸多控制因素中，岩体结构对这种岩体破坏方式的发育起了控制作用。夹泥型张裂隙与岸坡成大角度相交的陡倾角裂隙和缓倾角错动带组合并构成一个整体。缓倾角错动带的改造是前提。夹泥型张裂隙的发育则伴随陡倾角裂隙和缓倾角错动带的改造过程而产生，构成由陡倾角断裂或裂隙、缓倾角错动带组合形成的典型的岩体破坏模式。结合本地区构造特征和岩体结构特征，并通过大量的现场调查，该文主要探讨了坝区岩体结构特征和夹泥型张裂隙发育的关系，以及岩体结构对夹泥型张裂隙发育的控制作用。 相似文献
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丽香铁路金沙江特大桥位于金沙江虎跳峡镇高地震烈度深切峡谷地段。香格里拉端岸坡地形陡峻,卸荷裂隙发育,岸坡岩体在地震及工程荷载作用下的稳定性直接控制了桥梁选址方案的可行性。在深入分析对岸坡工程地质条件的基础上,基于节理特征分析的Barton模型、岩体结构面强度实验,讨论了岩体结构面强度参数,并在此基础上采用底摩擦实验研究了岸坡在自然和工程荷载作用下的稳定性,进而采用离散单元法计算分析了岸坡岩体在自然、桥基荷载作用下、地震加桥基荷载作用工况条件下的破坏趋势。研究表明,岸坡整体稳定,但在地震和桥梁荷载作用下,岸坡卸荷裂隙进一步发育,对桥基影响较大,应加强卸荷带岩体的工程整治以确保桥基安全。 相似文献
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金沙江某水电站上下坝址岩体卸荷差异研究 总被引：1，自引：1，他引：0
在河流下切、斜坡成坡过程中,斜坡应力场不断调整和适应坡体的变化,表浅部岩体在应力变化过程中往坡外发生卸荷,在同一地区岩体卸荷深度应当相差不大。而在西南某水电站相隔仅1.4km上下坝址勘察过程中发现,两坝址岩体卸荷深度却存在较大差异,上坝址岩体卸荷深度在20m以上,最大深度达到90m;下坝址岩体卸荷深度仅为5~20m。,通过现场调查及数值模拟成果表明,上下坝址岩层方位是两坝址岩体卸荷差异的决定性因素,上坝址为顺向坡,岩层走向与边坡走向平行,倾角较陡的岩层形成拉裂面,易于风化营力的侵入,岩体卸荷深度大;下坝址为横向坡,岩层走向与边坡走向近于垂直,岩体强度远大于岩层面的强度,且平行坡向的结构面数量少,岩体卸荷深度在20m以内。 相似文献
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三交坪滑坡位于四川首汉源县境内的流沙河左岸，分布面积约1km^3。由于该坡体存在层间错动带和局部变形碎裂体．且地表泉水点较多．造成坡体上游、中部及前缘出现了大量的拉裂缝，目前坡体局部已处于不稳定状态。因此，对该坡体的稳定性评价显得尤为重要。文章根据坡体的结构及形态特征详细分析了滑坡的形成演化机制，判定三交坪滑坡的破坏模式为蠕滑拉裂。同时采用岸坡岩体地质分析及量化评价方法对该滑坡的稳定性进行了分析，得出浅层计算滑面及基岩覆盖界面处的深部计算滑面在天然状态下稳定性良好；但在天然＋暴雨的条件下，浅部滑面的稳定性有少许弱化，处于临界不稳定状态。最后，根据以上分析提出合理的治理建议。 相似文献
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本文在大量的裂隙调查基础上,总结分析了西南某水电站坝址区中缓倾裂隙的地质特征,阐释了中缓倾裂隙的形成机制和发育模式。通过统计分析,结果表明:(1)岩坡中缓倾裂隙总体与岸坡大体平行,是河谷下切伴生的岸坡应力分异和卸荷回弹形成的表生压致拉裂破裂体系; (2)岸坡的形成是河谷多期次下切的结果,河谷下切坡度变陡,后期形成的中缓倾裂隙亦相对早期宽缓河谷形成的中缓倾裂隙倾角增大,河谷侧向偏移致使凸岸坡体更有利于保存早期裂隙,因此凸岸坡体中上部多见中倾裂隙与缓倾裂隙同时存在现象; (3)峡谷的形成总体是间歇性快速下切,相对稳定阶段岸坡形成表生中缓倾裂隙,快速下切期间以河谷垂向卸荷为主,由此形成与间歇性快速下切各阶段相对应的裂隙密集区和裂隙稀疏区的间断分布。 相似文献
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本文的研究通过黄河上游茨哈峡水电站岸坡的变形特征,阐明了一类顺层高陡斜坡由倾倒变形转化为蠕滑-拉裂的斜坡变形破坏方式、演变过程及发展趋势,并对该岸坡的稳定性进行了分析评价。结果表明,目前该斜坡变形的发展已初步形成潜在折断面,并正处于蠕滑-拉裂变形阶段。从地质历史过程分析,其处于从稳定变形到不稳定破坏的过渡阶段。 相似文献
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深切河谷岩体结构的表生改造 总被引：3，自引：0，他引：3
岩体结构的表生改造是指河谷下切过程中,由于应力释放,岸坡岩体将向临空面方向发生卸荷回弹变形,谷坡应力场产生新的调整,伴随这一过程岩体结构所产生的一系列新的变异或变化。岩体结构的表生改造一般具有两类形式,即原有构造或原生结构面的进一步改造,或新的表生破裂体系的形成。其结果是在河谷岸坡一定深度范围内,形成类似于地下硐室围岩“松动圈”的岸坡卸荷带,从而恶化岩体的工程性状,降低结构面强度,对工程具有明显的 相似文献
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小湾水电站坝址位于高山峡谷区,深切峡谷形成演化的动力学过程决定了坝区边坡目前的形态特征、岩体结构特征及稳定性状况,由此深刻影响边坡设计方案和建基面的选择。基于现场工作和分析测试成果,得出主要结论有:(1)由于河谷形成过程中的卸荷作用及风化作用,边坡浅表层改造强烈,产生了大量的中缓倾角裂隙,坡面附近近SN向陡裂张开、扩展;浅表层发育了大量近EW向挤压带(面);(2)岸坡浅表层中缓倾角结构面的产生机制,包括沿原构造节理扩展和新生裂隙;坡体下部的中缓倾角裂隙会因差异卸荷回弹而继续扩展,坡体中上部岩体质量劣化,在地应力场调整过程中,因剪切滑移继续扩展,坡体逐渐进入时效变形阶段。(3)对河谷边坡进行了地质—工程分类,指出各类边坡可能变形失稳模式包括倾倒变形、平面滑动、阶梯状滑动、楔形滑动和堆积体滑动等5种。 相似文献
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随着低碳能源的推行,大量水电站的兴建引发了大量库岸滑坡问题。库岸滑坡与普通滑坡有着显著区别,但在实际工程的稳定性计算过程中,工程人员常将二者归为一体,采用同样的思路和方法进行研究。为了更好地治理库岸滑坡,根据库岸自身的特点,在长期野外地质调查和室内文献调研的基础上,提出按结构面特征、坡体位置和滑体物质成分进行库岸斜坡分区的原则;针对库岸滑坡的特点,推导了被牵引段有推力+后缘拉裂面有剪力、被牵引段不存在推力+后缘拉裂面有剪力、被牵引段不存在推力+后缘拉裂面无剪力三种情况的水库岸坡滑坡稳定性计算公式;结合工程实例,验证基于水库岸坡特征滑坡稳定性计算修正传递系数法的正确性。 相似文献
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The possible application of a Rindler type reference frame for studies of physical processes near the horizons of black and white holes is considered. New similar reference frames inside black and white holes in the region T of a Kruskal wormhole are introduced. 相似文献
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A supernova explosion in a close binary system in which one of the components is a compact magnetized object (neutron star or white dwarf) can form a narrow “tail” with length l t ～109 cm, width h t ～108 cm, and magnetic field B t ～106, due to the resulting shock wave flowing around the magnetosphere of the compact object. The energy released by the reconnection of magnetic field lines in this tail can accelerate electrons to relativistic speeds (γ≈104), creating the conditions required for powerful synchrotron radiation at energies from hundreds of keV to several MeV, i.e., for a gamma-ray burst (GRB). The duration of this radiation will depend on the power of the shock that forms during the supernova. If the shock is not sufficiently powerful to tear off the magnetosphere tail from the compact object, the duration of the GRB will not exceed l t /V A ≤1 s, and the conditions necessary for an “afterglow” at softer energies will not arise. If the shock is more powerful, the tail can be torn from the magnetosphere, forming a narrow ejection, which is perceived in its relativistic motion toward the observer(Γ～104) as an afterglow whose duration grows from tens of seconds at gamma-ray energies to tens of days in the optical. This may explain why afterglows are observed only in association with long GRBs (T 90>10 s). Very short GRBs (T 90<0.1 s) may be local, i.e., low-power, phenomena occurring in close pairs containing compact, magnetized objects, in which there is again an interaction between the magnetosphere of the compact object and a shock wave, but the shock is initiated by a flare on the companion, which is a red-dwarf cataclysmic variable, rather than by a supernova. 相似文献
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This paper presents a theoretical approach to analyse coupled, linear thermoporoelastic fields in a saturated porous medium under radial and spherical symmetry. The governing equations account for compressibility and thermal expansion of constituents, heat sink due to thermal dilatation of water and thermal expansion of the medium, and thermodynamically coupled heat–water flow. It has been reported in the literature that thermodynamically coupled heat–water flows known as thermo-osmosis and thermal filtration have the potential to significantly alter the flow fields in clay-rich barriers in the near field of a underground waste containment scheme. This study presents a mathematical model and examines the effects of thermo-osmosis and thermal-filtration on coupled consolidation fields in a porous medium with a cavity. Analytical solutions of the governing equations are presented in the Laplace transform space. A numerical inversion scheme is used to obtain the time-domain solutions for a cylindrical cavity in a homogeneous or a non-homogeneous medium. A closed form time-domain solution is presented for a spherical cavity in a homogeneous medium. Selected numerical solutions for homogeneous and non-homogeneous media show a significant increase in pore pressure and displacements due to the presence of thermodynamically coupled flows and a negligible influence on temperature. © 1998 John Wiley & Sons, Ltd. 相似文献
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M. Yu. Reshetnyak 《Astronomy Reports》2016,60(2):294-305
The dependences of the magnetic-field strength, variations of the magnetic field, and the multipole level on the amplitudes of the α and ω effects are considered using a two-dimensional model for a Parker dynamo in a spherical layer. Calculations have been carried out for both traditional spatial distributions of α and ω and geostrophic regimes obtained from three-dimensional modeling of thermal convection. Two-dimensional distributions of the dynamo-wave velocities in the zone where magnetic field is generated are presented. Comparisons with the solar and planetary dynamos are considered. 相似文献
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A. N. Galybin 《国际地质力学数值与分析法杂志》1998,22(3):175-196
The problem of the equilibrium of a plane with a circular hole and a shear crack is considered to model failure of an excavation (borehole or circular opening) in rocks weakened by discontinuities (planes of weakness). It is assumed that sliding occurs in a part of the plane of weakness when the Mohr–Coulomb friction criterion is satisfied due to the stress redistribution caused by the excavation. The method of singular integral equations is employed to solve the boundary value problem. Geomechanical problems concerning borehole breakout and rockburst caused by fault-opening interaction are discussed. © 1998 John Wiley & Sons, Ltd. 相似文献
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The focus of this contribution is to develop a complex variable function method to solve the two-dimensional scattering of plane waves by a lined cylindrical cavity in the poroelastic half-plane. The poroelastic half-plane is based on Biot’s dynamic theory, and the governing equations are solved by reduction to three Helmholtz equations. The lining structure can be treated as an elastic material and decoupled into two Helmholtz equations. Here, the large circle assumption is applied to simulate the half-plane boundary. By using appropriate boundary conditions and continuity conditions, the unknown coefficients in the potentials can be determined. Selected numerical results are presented in this paper. 相似文献
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Victor Ryzhik 《Computational Geosciences》2007,11(1):1-8
Spreading of a non-aqueous phase liquid (NAPL) denser than water (DNAPL) lens (mound) in the unsaturated zone of double-porosity
aquifer above an impervious plane boundary is investigated. The double-porosity aquifer is conceptualized as a fracture network
surrounding pervious blocks. Vertical gravity equilibrium is assumed to prevail in each one of the two media, fractures and
blocks. Through vertical integration, two coupled partial differential equations for the DNAPL content in each medium are
obtained. The mass exchange rate between high- and low-permeability media is considered as a function of NAPL content. The
dominant effect is gravity, whereas capillary forces are negligible. Analytical solutions for one-dimensional and axisymmetric
problems of mound spreading are obtained. 相似文献
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Summary Any rock may be regarded as an aggregate of mineral species frequency distributions, thus opening up a new method of analyzing the problems of the nature of these discrete distributions.Based on theorems in mathematical probability, a subrock sample is defined as a probability sample under the conditions that every mineral species' distribution function in this subrock converges probabilistically to one and the same distributions the nature of which is immaterial at this point.For obvious reasons, the situation is excluded if the sample size approaches infinity, i.e., Chebyshev's theorem (Chebyshev, 1867). 相似文献
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Strain analysis of a shear zone in a granodiorite 总被引：1，自引：0，他引：1
A ductile shear zone in a late Precambrian granodiorite, from the Rouergue (southwest part of the French Massif Central) has been studied.A single episode of deformation is responsible for the formation of a foliation and a well-defined lineation which are localized into an elongated zone, a few decimeters wide.The strain features can be attributed to a simple-shear mechanism (Ramsay and Graham, 1970), so that the main parameters of the deformation are defined.At stages of increasing deformation, the quartz isotropic sub-fabric of the undeformed host rock is progressively transformed into an anisotropic fabric composed of a single oblique girdle while the subgrain size progressively decrease and the dislocation density remains constant. It is suggested that the gliding planes of quartz are the basal plane (0001) and a predominant prismatic plane 101̄0 the slip directions may be a for both glide-planes.The results obtained in this investigation provide a basis for a high voltage electron microscope (H.V.E.M.) study which shows that the fabrics development may be related to dislocation processes. The difference of strain rates in the host rock and in the shear zone is calculated from the dislocation microstructures. 相似文献